Pycharm : not displaying files on the left

Question

I used to have my files on the pycharm box on the left of my window, like that : but now Pycharm displays it under the list of directory :

I can't change of directory on the left part of the window : I have to use the horizontally-stacked list of folders, which is really annoying. Which switch in the conf of Pycharm do I have to check to have the normal behaviour back ?

Answer 1

It was a corrupted project settings, I had to close PyCharm and remove .idea folder in the project root to make it work.